WAYS TO SUPPORT Register Understanding the natural history of STXBP1 is essential to discovering improved treatments. Whether it is a repur- posed drug or a novel therapy, validation in a controlled manner is paramount to understanding efficacy and conse- quently improving the lives of our STXBP1 patients. Families can register with Simons Searchlight by visiting simonssearchlight.org. Caregivers need only supply a ge- netic report confirming diagnosis to get started. Participate in Research Participating in or initiating research is essential to finding better therapies. Research onSTXBP1 is grossly un- derfunded; your support is critical to changing the current Lead paradigm. the Spread Awareness STXBP1 is rare and our families often go for years Charge without the correct diagnosis. Your support in understand- ing the need for genetic analysis and communicating with For a your colleagues and patients is important to getting our families the information they so desperately need. Cure Contribute Whether it is your time or your money, this rare disor- der represents an opportunity to make a meaningful and profound impact on STXBP1 patients’ lives. We hope you will support us today! stxbp1disorders.org stxbp1disorders.org [email protected] [email protected] WHAT IS STXBP1 DISORDER? Diagnosis STXBP1 disorder is an autosomal dominant disease, STXBP1 diagnosis is made through molecular genetic test- resulting from de novo mutations in the STXBP1 gene, ing, through a panel test, exome testing or chromosom- which affects the brain and nervous system, due to impair- al microarray analysis. The genetic testing results would ment of transmission between nerve cells. Patients with the identify a pathogenic heterozygous variant in STXBP1, or disorder typically have some of these symptoms: early onset a contiguous gene deletion that includes STXBP1 and pos- epilepsy, global delay, cognitive impairment (mild to pro- sibly adjacent genes. found), movement disorders, and autism spectrum. Treatment Incidence Commonly used antiepileptic drugs (AEDs) are phenobar- The disorder occurs in countries, populations, and ethnic bital, valproic acid, and vigabatrin. In an estimated 20% of groups around the world. The total number of STXBP1 pa- individuals, two or more AEDs are used in combination. tients diagnosed to date based on genetic testing is estimat- Approximately 25% of patients do not respond to AED ed at 300-400 people worldwide. The estimated incidence therapy. Severe dystonia, dyskinesia, and choreoathetosis of STXBP1 is 1 in 90,000 based on a 2016 Danish study, can be treated with monoamine depleters or dopaminergic although the true prevalence of the disease is unknown, agents (Khaikin et. al.2016). as many cases go under- or misdiagnosed (Stamberger et.al. 2016). Supportive Care Because patients with STXBP1 disorder have a wide range of clinical manifestations and functional challenges, they are best followed by a multidisciplinary team. Many pa- tients benefit from physical, occupational, feeding and speech therapies. Long-Term Prognosis Due to the rarity of and newness of molecular genetic test- ing for STXBP1, at this time only anecdotal information exists on long-term survival. Some STXBP1 patients are in their 20’s, 30’s and even 50’s. References Stamberger H., et. al. STXBP1 encephalopathy: A neurodevelopmental disorder including epilepsy. Neurology. 2016. 86(10): 954-62. Khaikin Y., Mercimek-Mahmutoglu S. STXBP1 Encephalopathy with Epilepsy. GeneReviews Seattle (WA). 1993-2017. Signs & Symptoms The median age of onset of seizures is six weeks (range 1 day to 13 years). Seizure types can include infantile spasms; generalized tonic-clonic, clonic or tonic seizures; and my- oclonic, focal, atonic, and absence seizures. Epilepsy syndromes can include: Ohtahara syndrome, West syndrome, Lennox-Gaustaut syndrome, and Dravet syndrome. Five percent of STXBP1 patients do not exhibit seizures. The clinical spectrum of STXBP1 is heterogeneous and broad, with features overlapping other genetic disor- ders including: SCN1A, MECP2, and KCNQ2. Symptoms may include: early-onset epileptic encephalopathy, glob- al developmental delay, feeding difficulties, gross motor, fine motor and other movement difficulties. Intellectu- al disability and autism features are also common. Some patients receive a diagnosis of Cerebral Palsy as the cause of disease. While most patients are nonverbal, some families report their children learning to speak and/or sign..